For controlling the tone of silver images, there are known compounds containing sulfur atoms, which are easily adsorbed to silver (for example, mercapto compounds and thiazoline-thione compounds). However, since these compounds are easily adsorbed to silver halides, there are problems in that adsorption of sensitizing dyes are inhibited, sensitivity is reduced and remarkable blackening of images due to auxiliary exposure can not be prevented. The image blackening due to anxiliary exposure (i.e., post exposure) occurs in the situation where the photosensitive material is left in a dark room for a long period of time before development after imagewise exposure. In this case, the entire light-sensitive material is developed and finished blackishly by the exposure to safe-light in a dark room which reduces the image contrast and degrades the overall appearance.
If the above-mentioned phenomenon should occur, the value as the photographic material is remarkably degraded.
It has been surprisingly found that the remarkable blackening phenomenon to images due to auxiliary exposure can be prevented by the use of the compound according to the present invention.